Lets say if there was an experiment in which: A toy car with modelling clay attached to it, and a pellet is fired at it, the pellet sticks into the clay and the toy car moves forward. Now if it is replaced with a metal plate attached to the toy car instead of the clay, the pellet rebounds of the plate and the car moves forward, however a greater speed is reached by the toy car. Now to explain this, is it because: The modelling clay absorbs some of the energy provided by the pellet, meaning less energy is dissipated to the car. The energy is dissipated more to the toycar when the metal plate is attached. But do I have to mention due to the structure? Also by saying more energy goes towards the car, can saying 1/2MV^2= Ek so if more energy, and mass remains constant surely means, V increases.